The proposed study explores mechanisms consistent with social learning theory that operate within social networks. It specifies how the specific social environments are mediated by the networks to influence health behaviors, e.g., acculturation results in changing networks whose properties then influence health behaviors, as proscribed by ecological frameworks of behavior (Hovell et al. In Press;Glass et al. 2005). It will increase knowledge of how social networks and the social environment influence alcohol consumption and related health risks and the role that immigration and acculturation play in that process among two first generation, rapidly growing, immigrant groups in the United States. First generation Koreans and Mandarin speaking Chinese experience the disruptive, stressful, and sometimes traumatic experiences associated with immigration to the U.S. and these may lead to problems with alcohol. The study also investigates ecological influences (e.g., enforcement of laws, gender, current and traditional cultural norms, etc.) on the types of social networks that develop, (e.g., extent of network ethnic exclusivity) and the combined influences of evolving networks and ecology on health risks. We address these concerns by investigating how social network patterns and their influence on drinking behaviors vary by acculturation, length of residence in the U.S., age, gender, residential location, and differ from that in the country of origin using reports describing previous and current networks. The specific aims for the study are to: 1) To identify and describe social networks and changes in these networks that first generation Korean and Chinese immigrants experience upon immigration, and how these networks evolve with time, and 2) to test hypotheses involving associations between specific endogenous and exogenous characteristics of social networks and health risks involving alcohol. This study will inform the design of health interventions through social networks to efficaciously reduce alcohol related health risks. The proposed study explores the mechanisms within social networks, including social learning variables (including the presence of models of behavior, social support, self efficacy to control drinking, and others), acculturation, and ecological variables and their effects on drinking inside and outside the social network, and among first generation Chinese and Korean immigrants to the U.S. It is designed to produce information concerning targets for public health interventions to reduce health risks due to alcohol for subsequent interventions.